Copper-Zeolites as Catalysts for the Coupling of Terminal Alkynes: An Efficient Synthesis of Diynes

Cu-I-modified zeolites, especially Cu-I-USY, proved to be very efficient catalysts for the homocoupling of terminal alkynes. Such heterogeneous catalysts offer a very simple (no added ligand) and convenient synthesis of diynes, including carbohydrate derivatives. A strong influence of the zeolite pore size has been observed, high (quantitative) yields being obtained with zeolites having large internal cages. The role of zeolite acidic sites in the reaction has been pointed out. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)